1. Field
One embodiment of the present invention relates to a head-separated camera device and a control method thereof in which a camera head and a CCU (camera control unit) for controlling the camera head are separate from each other.
2. Description of the Related Art
As is known well, a head-separated camera device as described above is configured such that, for example, a camera head and a CCU are respectively constituted as separate members both connected mutually through a camera cable which bundles plural signal lines. The camera head comprises a solid-state imaging element such as a CMOS (complementary metal-oxide semiconductor) sensor. The CCU supplies a drive control signal to a solid-state imaging element of the camera head, and obtains a video signal by performing a signal processing on an output from the solid-state imaging element.
Recently, modifications aiming for much higher function and performance have been made to the head-separated camera device. Accordingly, types and bit rates of signals which are transferred between the camera head and the CCU have been increasing greatly. The number of signal lines bundled in the camera cable has therefore increased and thickened the camera cable itself, and the number of terminals provided on a connector for connecting the camera cable and the camera head has also increased and resulted in that the connecter tends to have a larger size.
In general, head-separated camera devices are developed for the purpose of, for example, visually inspecting narrow areas where people cannot enter and camera heads thereof are demanded to be downsized as much as possible. Therefore, thickening of a camera cable and upsizing of a connector for connecting a camera cable are considered as factors which hinder downsizing of camera heads, and hence involve a serious problem to be avoided.
Jpn. Pat. Appln. KOKAI Publication No. 10-254825 discloses a technique of reducing the number of terminals in a semiconductor integrated circuit by common use of any communication terminal and any other terminal (such as a reference voltage terminal) among three bus lines in a semiconductor integrated circuit which comprises communication terminals for data communication and is equipped with a data communication function according to a three-line-type serial data transfer scheme.
Jpn. Pat. Appln. KOKAI Publication No. 11-252438 discloses a technique of reducing the number of cables between a camera head unit and a main camera unit by adopting a configuration as follows. A composite synchronization signal and a control signal of the camera head unit are transferred, multiplexed with each other, from the main camera unit to the camera head unit. A composite synchronization signal, a status signal of the camera head unit, and a video signal are transferred, multiplexed with each other, from the camera head unit to the main camera unit.